Section 1.5

Vocabulary


plate- separate sections of the lithosphere

scientific theory- a well-tested that explains a wide range of observations

plate techtonic -the geological theory that states that pieces of Earth's lithisphere are in constant slow motion, driven by convection currents in the mantle

transfer boundary-a place where two plates slip past eachother, moving in opposite directions

divergent boundary-the place where two plates move apart

rift valley-a deep valley

convergent boundary-the place where two plates come together

Outline


T=The Theory of Plate Techtonics

Summary
-Earth's lithosphere broken into pieces separated by jagged cracks
-J.Tuso Wilson discovered that lithosphere is broken into separate sections called plates
-plates carry continents, or parts of the ocean floor, or both

A Theory of Plate Motion
-Wilson combined knowledge of sea-floor spreading, Earth's plates, and continental drift into one theory, the theory of plate tectonics
-plates of lithosphere float on top of asthenosphere
-convection currents rise in asthenosphere and spread beneath lithosphere, flow of currents causes movemaent of plates
-as they move they collide, pull apart, grind past each other causes volcanoes, mountain ranges, and deep-sea trenches to form

Plate Boundaries
-edges of plates meet at lines called plate boundaries, extend deep into lithosphere
-faults form along boundaries
-three kinds of plate boundaries, transform boundaries, divergent boundaries, and convergent boundaries
-transform boundary is where two plates slip past each other, moving in opposite directions
-divergent boundaries are the place where two plates move apart, or diverge
-most occur in mid-ocean ridge
-when divergent boundary occurs in land rift valley forms along divergent boundary, someday rift might split apart
-convergent boundary is where two plates come together, or converge
-different kinds of convergent boundaries

The Continents' Slow Dance
-plates move one to ten centimeters per year
-260 million years ago continents were joined together ina single land mass called
Pangaea
-225 million years ago Pangaea began to break apart